autism

Children with autism lack visual skills required for independence

February, 2011

Autism is popularly associated with intense awareness of systematic regularities, but a new study shows that the skill displayed in computer tasks is not available in real-world tasks.

Contrary to previous laboratory studies showing that children with autism often demonstrate outstanding visual search skills, new research indicates that in real-life situations, children with autism are unable to search effectively for objects. The study, involving 20 autistic children and 20 normally-developing children (aged 8-14), used a novel test room, with buttons on the floor that the children had to press to find a hidden target among multiple illuminated locations. Critically, 80% of these targets appeared on one side of the room.

Although autistics are generally believed to be more systematic, with greater sensitivity to regularities within a system, such behavior was not observed. Compared to other children, those with autism were slower to pick up on the regularities that would help them choose where to search. The slowness was not due to a lack of interest — all the children seemed to enjoy the game, and were keen to find the hidden targets.

The findings suggest that those with ASD have difficulties in applying the rules of probability to larger environments, particularly when they themselves are part of that environment.

Reference: 

[2055] Pellicano, E., Smith A. D., Cristino F., Hood B. M., Briscoe J., & Gilchrist I. D.
(2011).  Children with autism are neither systematic nor optimal foragers.
Proceedings of the National Academy of Sciences. 108(1), 421 - 426.

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Children with autism have distinctive patterns of brain activity

December, 2010

An imaging study has found three different brain signatures discriminating children with autistic spectrum disorders, siblings of children with ASD, and other typically-developing children.

Last month I reported on a finding that toddlers with autism spectrum disorder showed a strong preference for looking at moving shapes rather than active people. This lower interest in people is supported by a new imaging study involving 62 children aged 4-17, of whom 25 were diagnosed with autistic spectrum disorder and 20 were siblings of children with ASD.

In the study, participants were shown point-light displays (videos created by placing lights on the major joints of a person and filming them moving in the dark). Those with ASD showed reduced activity in specific regions (right amygdala, ventromedial prefrontal cortex, right posterior superior temporal sulcus, left ventrolateral prefrontal cortex, and the fusiform gyri) when they were watching a point-light display of biological motion compared with a display of moving dots. These same regions have also been implicated in previous research with adults with ASD.

Moreover, the severity of social deficits correlated with degrees of activity in the right pSTS specifically. More surprisingly, other brain regions (left dorsolateral prefrontal cortex, right inferior temporal gyrus, and a different part of the fusiform gyri) showed reduced activity in both the siblings group and the ASD group compared to controls. The sibling group also showed signs of compensatory activity, with some regions (right posterior temporal sulcus and a different part of the ventromedial prefrontal cortex) working harder than normal.

The implications of this will be somewhat controversial, and more research will be needed to verify these findings.

Reference: 

[1987] Kaiser, M. D., Hudac C. M., Shultz S., Lee S. M., Cheung C., Berken A. M., et al.
(2010).  Neural signatures of autism.
Proceedings of the National Academy of Sciences.

Full text available at http://www.pnas.org/content/early/2010/11/05/1010412107.full.pdf+html

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Autism study reveals how a genetic variant rewires the brain

December, 2010

An imaging study has revealed how one of the many genes implicated in autism is associated with an atypical pattern of connectivity between the hemispheres and within and from the frontal lobe.

Many genes have been implicated in autism; one of them is the CNTNAP2 gene. This gene (which is also implicated in specific language disorder) is most active during brain development in the frontal lobe. An imaging study involving 32 children, half of whom had autism, has revealed that regardless of their diagnosis, the children carrying the risk variant showed communication problems within and with the frontal lobe. The frontal lobe was over-connected to itself and poorly connected to the rest of the brain, particularly the back of the brain.

There were also differences in connectivity between the left and right sides of the brain — in those with the non-risk gene, communication pathways in the frontal lobe linked more strongly to the left side of the brain (which is more strongly involved in language), but in those with the risk variant, the communications pathways connected more broadly to both sides of the brain.

The findings could lead to earlier detection of autism, and new interventions to strengthen connections between the frontal lobe and left side of the brain. But it should be emphasized that the autistic spectrum disorders probably encompass a number of different genetic patterns associated with different variants of ASD.

It should also be emphasized that this gene variant, although it increases the risk of various neurodevelopmental disorders (such as specific language impairment, which has also been associated with this gene), is found among a third of the population. So the pattern of connectivity, although not ‘normal’ (i.e., the majority position), is not abnormal. It would be interesting to explore whether other, more subtle, cognitive differences correlate with this genetic difference.

Reference: 

Scott-Van Zeeland., A.A. et al. 2010. Altered Functional Connectivity in Frontal Lobe Circuits Is Associated with Variation in the Autism Risk Gene CNTNAP2. Science Translational Medicine, 2 (56), DOI: 10.1126/scitranslmed.3001344 http://stm.sciencemag.org/content/2/56/56ra80.abstract

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Girls less likely to be diagnosed autistic even when symptoms severe

December, 2010

A new study finds that gender and maternal assertiveness are factors in determining whether children with autistic symptoms are diagnosed with ASD.

No one is denying that boys are far more likely to be autistic than girls, but a new study has found that this perception of autism as a male disorder also means that girls are less likely to be diagnosed with autistic spectrum disorder (ASD) even when their symptoms are equally severe.

Another factor affecting diagnosis was maternal age — those diagnosed with ASD were likely to have older mothers. It’s suggested that this may be because older mothers are better at identifying their children's difficulties and have more confidence in bringing concerns to the clinic. This is supported by the finding that first-born children were less likely to be diagnosed with ASD, as were children of mothers with depression.

Ethnic origin, maternal class and mother's marital status did not significantly predict a child either having an ASD diagnosis or displaying severe autistic traits.

The findings were based on an analysis of data from a longitudinal UK cohort study, the Avon Longitudinal Study of Parents and Children (ALSPAC).

Reference: 

Russell, G., Steer, C. & Golding, J. 2010. Social and demographic factors that influence the diagnosis of autistic spectrum disorders. Social Psychiatry and Psychiatric Epidemiology. DOI 10.1007/s00127-010-0294-z.
Full text is available at http://springerlink.com/content/a67371l826m1xl76/fulltext.pdf

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An early marker of autism

October, 2010

A strong preference for looking at moving shapes rather than active people was evident among toddlers with autism spectrum disorder.

A study involving 110 toddlers (aged 14-42 months), of whom 37 were diagnosed with an autism spectrum disorder and 22 with a developmental delay, has compared their behavior when watching a 1-minute movie depicting moving geometric patterns (a standard screen saver) on 1 side of a video monitor and children in high action, such as dancing or doing yoga, on the other.

It was found that only one of the 51 typically-developing toddlers preferred the shapes, but 40% of the ASD toddlers did, as well as 9% of the developmentally delayed toddlers. Moreover, all those who spent over 69% of the time focusing on the moving shapes were those with ASD.

Additionally, those with ASD who preferred the geometric images also showed a particular pattern of saccades (eye movements) when viewing the images — a reduced number of saccades, demonstrated in a fixed stare. It’s suggested that a preference for moving geometric patterns combined with lengthy absorption in such images, might be an early identifier of autism. Such behavior should be taken as a signal to look for other warning signs, such as reduced enjoyment during back-and-forth games like peek-a-boo; an unusual tone of voice; failure to point at or bring objects to show; and failure to respond to their name.

Reference: 

[1891] Pierce, K., Conant D., Hazin R., Stoner R., & Desmond J.
(2010).  Preference for Geometric Patterns Early in Life As a Risk Factor for Autism.
Arch Gen Psychiatry. archgenpsychiatry.2010.113 - archgenpsychiatry.2010.113.

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Sensory integration in autism

October, 2010

A new study provides evidence for the theory that sensory integration is impaired in autism.

Children with autism often focus intently on a single activity or feature of their environment. A study involving 17 autistic children (6-16 years) and 17 controls has compared brain activity as they watched a silent video of their choice while tones and vibrations were presented, separately and simultaneously.

A simple stimulus takes about 20 milliseconds to arrive in the brain. When information from multiple senses registers at the same time, integration takes about 100 to 200 milliseconds in normally developing children. But those with autism took an average of 310 milliseconds to integrate the noise and vibration when they occurred together. The children with autism also showed weaker signal strength, signified by lower amplitude brainwaves.

The findings are consistent with theories that automatic sensory integration is impaired in autism, and may help explain autism’s characteristic sensitivity to excessive sensory stimulation.

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New technology can help assess autistic & language disorders

August, 2010

New technology offers hope of early diagnosis of both autism spectrum and language disorders, as well as promising help to parents in assessing the effectiveness of therapy.

A new automated vocal analysis technology can discriminate pre-verbal vocalizations of very young children with autism with 86% accuracy. The LENA™ (Language Environment Analysis) system also differentiated typically developing children and children with autism from children with language delay. The processor fits into the pocket of specially designed children's clothing and records everything the child vocalizes. LENA could not only enable better early diagnosis of autism spectrum disorders, but also allow parents to continue and supplement language enrichment therapy at home and assess their own effectiveness for themselves.

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Early intervention for toddlers with autism highly effective

January, 2010

A study involving autistic toddlers has found a novel early intervention program to be effective for improving IQ, language ability, and social interaction.

A five-year study involving 48 diverse, 18- to 30-month-old children with autism and no other health problems has found a novel early intervention program to be effective for improving IQ, language ability, and social interaction. The Early Start Denver Model combines applied behavioral analysis (ABA) teaching methods with play-based routines that focused on building a relationship with the child. Half the children received two two-hour sessions five days a week from specialists (but in their own homes) plus five hours a week of parent-delivered therapy. The remaining children were referred to community-based programs. After two years, the IQs of the children in the intervention group had improved by an average of around 18 points, compared to a little more than four points in the comparison group. The intervention group also had a nearly 18-point improvement in receptive language (listening and understanding) compared to around10 points in the comparison group. Seven of the children in the intervention group received an improved diagnosis from autism to the milder condition known as 'pervasive developmental disorder not otherwise specified' (PDD-NOS), compared to only one child in the community-based therapy group.

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Task determines whether better for neurons to generalize or specialize

July, 2010

A monkey study reveals that, although some neurons are specialized to recognize specific concepts, most are more generalized and these are usually better at categorizing objects.

Previous research has found that individual neurons can become tuned to specific concepts or categories. We can have "cat" neurons, and "car" neurons, and even an “Angelina Jolie” neuron. A new monkey study, however, reveals that although some neurons were more attuned to car images and others to animal images, many neurons were active in both categories. More importantly, these "multitasking" neurons were in fact the best at making correct identifications when the monkey alternated between two category problems. The work could lead to a better understanding of disorders such as autism and schizophrenia in which individuals become overwhelmed by individual stimuli.

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